NATO will hold two more conferences aimed at pushing member states to commit more troops to the alliance's mission in Afghanistan as it faces tough resistance from insurgents there, a spokesman said Saturday.

Military leaders decided after two days of closed-door discussions in the Polish capital that further efforts were needed to plug shortfalls in the force, which has faced increased violence from a resurgent Taliban along Afghanistan's southern border, NATO spokesman Col. Brett Boudreau told The Associated Press.

Earlier Saturday, Gen. Ray Henault, chairman of the NATO military committee, said he would appeal formally to the alliance's council Monday for member states to commit another 2,000-2,500 soldiers to confront the Taliban guerrillas.

NATO military leaders also will hold further conferences on Wednesday and Friday to address the issue of the shortfall of troops in southern Afghanistan and urge member states to live up to the numbers they had pledged to the mission, Boudreau said. Commitments to other missions also will be discussed.

Last week, alliance commander Gen. James L. Jones called for extra troops and aircraft to be sent to southern Afghanistan, where NATO relieved U.S.-led troops one month ago.

But the appeals were running into donor fatigue from several key NATO members, many of whom have indicated they had reached the limit of their capabilities.

"Afghanistan is the most complex mission NATO has ever undertaken," Henault said. "Our collective assessment is that we are satisfied with the military-related progress to date, particularly in the north and the west, but less so in the south, where it's been more difficult."

Henault said only 85 percent of forces required for the mission have been supplied by the member nations so far.

That was "considered acceptable by the commanders ... to undertake the level of mission activity that they had anticipated ... until they discovered the intensity of the resistance" from Taliban forces, he said.

The NATO military leaders' conference on Wednesday will "look to obtain the people and the equipment required to bring that 85 percent as close to 100 percent as possible," Boudreau said.

The second meeting will "look at addressing a shortfall in the immediate requirement and for subsequent rotation of forces" that the alliance has on other missions.

Some 20,000 NATO soldiers and a similar number of U.S. forces in Afghanistan face an emboldened Taliban insurgency that demonstrates how shaky Afghanistan's Western-backed government remains.

Jones is seeking reinforcements for the 8,000 mainly British, Canadian and Dutch troops that took over the region in August. Fighting since then has left at least 35 NATO troops and hundreds of militants dead.